In vehicles which are equipped with automatic transmissions, the shift lever is movable from a park position to other gear positions such as reverse, neutral, drive, second gear and first gear. The shift lever is generally associated with a detent plate and detent pawl for releasably holding the lever in the park position, and an actuator means is provided for actuating the pawl to release the shift lever for movement to the other gear positions. The actuator means most commonly utilized in these shifters involves mechanical actuating means which require some degree of sophistication during assembly to assure manufacture of a high quality product, and also requires several unique parts for the assembly. Hence, alternative designs using standardized parts and which are easier to assemble with less chance of error are desired.
Also, in shifting from the park position to the other gear positions, problems have been encountered in the unattended acceleration of the vehicle and, therefore, efforts have been made to prevent the shifting of the shift lever until the brake pedal has been depressed or other preconditions are satisfied so that the vehicle will not move before it is intended by the driver. The efforts thus far have generally been directed to mechanically or electrically actuated mechanisms for blocking the movement of the detent pawl until such time as the preconditions are satisfied. The result is that these mechanisms have become very complicated. Further, these mechanisms tend to include multiple moving parts which involve extra assembly and cost. For example, typically, a blocking member is movably mounted to the shift mechanism and is manually or electrically moved between a blocking position so that the blocking member physically prevents the pawl from disengaging the detent plate, and a release position so that the blocking member allows shift lever to move. U.S. Pat. No. 5,096,033 discloses an example of such an arrangement.
However, these blocking members by design, only provide for an indirect control of the pawl. Further, the known constructions emphasize mechanical mechanisms which are costly to manufacture and assemble at a level of quality which is necessary in this application. Further, the mechanical mechanisms are often difficult to adapt to various shifter designs and require special parts, tooling, and testing procedures.
An object of the present invention is to provide a simplified lower cost version of a shift mechanism for preventing a driver from shifting a shift lever from park gear position to another gear position unless the brake is applied.
Another object is to provide a detent mechanism which is readily adaptable to a variety of different vehicle shifter and electrical systems.